President Victor Paz Estenssoro's decision to summon the U.S. military in a joint antidrug operation reflects the desperation of his struggle against a powerful group of traffickers whose illicit activities have become both the life blood of the Bolivian economy and a mortal threat to the government's political control.

Bolivia's new resolve is a victory for U.S. officials who have persistently pressed authorities here to crack down on the country's endemic drug trade, which many have thought nearly impossible to combat. The highly unusual invitation to bring American troops into Bolivia's drug war is a surprising shift from traditional reluctance by many Latin American countries to involve the U.S. military in their domestic affairs.

The cocaine lords had operated with relative impunity under previous governments that either collaborated with them or were too weak to control them. Paz Estenssoro, in moving forcefully against them, is risking further erosion of Bolivia's impoverished economy and violent counterattacks by the drug organization.

Most worrisome for Bolivian authorities has been what government officials perceive as a growing political threat from the traffickers. While there appear to be few concrete signs that Bolivian drug lords may be moving to overthrow the government, they are known to have financed the campaigns of certain candidates for local and national office and have recently acquired controlling interest in legitimate businesses, including several banks.

Against a backdrop of Bolivia's worst econcomic crisis in 50 years, the huge fortunes amassed by the drug organizations have induced fears of the loss of government control to the traffickers.

"If we do not address this narcotics problem decisively -- to eliminate it -- the day could come when the economic power they wield could result in their governing the country, including via democratic means," Paz Estenssoro said in an interview earlier this month in Newsweek magazine's international edition. "Election campaigns cost more and more every day, and the economic influence of the cocaine mafia could lead to unexpected results in terms of who runs the country."

Cocaine, he added, had "gained an importance in our economy in direct response to the shrinking of the formal economy."

But in attempting to dampen the drug trade, the government stands to knock away the economy's most profitable pillar at a time when the collapse in world prices of minerals and tin have seriously eroded Bolivia's mining industries, historically the main support of the economy.

Bolivian authorities estimate that the cocaine economy brings in about $600 million a year, which exceeds Bolivia's projected 1987 federal budget of $500 million. Illegal profits earned from narcotics pay for large-scale contraband imports, mostly consumer goods.

The failure of a U.S.-sponsored program to eradicate the coca crop, from which cocaine in manufactured, has also threatened to decrease the amount of U.S. aid Bolivia is entitled to receive.

Despite media reports exposing the planned raids before their scheduled launch later this week, Bolivian and U.S. officials here remained tightlipped today about the operation. An understanding had been worked out, before the operation became public, between U.S. diplomats and Bolivian authorities to let the Bolivians make the first formal announcement.

But Bolivian newspapers broke the story yesterday after noticing the arrival of U.S. aircraft and equipment at the main airport in the city of Santa Cruz. The premature publicity has put officials here in the awkward position of trying to protect the project's security, especially the exact location of the base of operations near the town of Trinidad in the Beni region, while coping with the flood of press queries.

Targeted for destruction by the U.S. airlift of Bolivian police troops are large clandestine laboratories in the Beni, a lush lowlands region in northeastern Bolivia, where jungle growth provides good cover for facilities used to process coca paste into cocaine. U.S. Drug Enforcement Administration officials have known the location of many of the hidden labs for months, but Bolivia's U.S.-trained antinarcotics police unit has been unable to attack because it has no aircraft.

Bolivian officials would prefer to go after the drug labs and landing strips used to ferry cocaine abroad than to continue with faltering efforts at eradicating vast areas of coca leaves, the raw material for cocaine. On again, off again eradication attempts have encountered fierce resistance from thousands of peasants who survive by growing and selling coca and who also constitute much of the political base of Paz Estenssoro's party, the Nationalist Revolutionary Movement.

Three months after taking office in August, Paz Estenssoro tried to give new impetus to the eradication program. It negotiated with the peasants' union in the Chapare region an arrangement under which people who voluntarily abandon coca cultivation would receive $350 per hectare, or 2.5 acres.

But this financial incentive proved insufficient to induce farmers to quit a crop from which they could gross, at peak prices a year ago, as much as $10,000 to $14,000 per hectare.

A little more than $7 million in U.S. assistance is being withheld because of Bolivia's inability to meet eradication goals set in 1983.